Evaporator



June 3, 194 B. c. JOHNSON ETAL EVAPORA TOR Filed M y 10, 1940 3Sheets-Sheet l Jul le 3, 1941.

B; C. JOHNSON ETAL,

EVAPORATOR Y Filed 'May 10, 1940 3 Sheets-She et 2 v June 1941- 'B. c.JOHNSON ETAL 2,244,010

EVAPORATOR Filed May 10, 1940 3 Sheets-Sheefi 3 Patented June 3, 1941UNITED STATES) PATE NT OFFICE.

Evhromrroa 7 Bernard C. Johnson, Libertyville. and Edgard C.

Franco-Ferreira, Chicago, fIll., assignors to- Houdaille-HersheyCorporation, Detroit, Mich,

a corporation of Michigan Application May [10, 1940,;Serial No. 334,3068 Claims. (cl. 62-41%) This invention relates to sheet metal heatexchangers such as evaporator units for mechanical refrigerators andmore specifically relates to wick,

constructions in evaporator units for automatically returning oilentrained in refrigerant in the evaporator unit back to the compressorsof the mechanical refrigerating systems.

In refrigerating systems of the compressorcondenserevaporator type, oilfrom the compressor'finds its way with the refrigerant to the evaporatorunit. Many devices have been proposed for trappin this oil in order thatthe same can be returned to the compressor for performing itslubricating function. Such devices, however, have been expensive andcomplicated.

The present invention now ,provides a simple,.v

inexpensive wck means for returning oil from evaporator units back tothe compressor without short-circuiting the refrigerant flow or in any.way causing the flow of refrigerant back to the compressor before ithas completed its heat-absorbing function.

The wick means of the present invention are especially adapted for usein refrigerating systems employing sulphur dioxide as a refrigerant.-

The lubricating oil used in such systems will not dissolve in thesulphur-dioxide to any great extent at the evaporator temperature.According- 1y, it has now been found that the use of a simple wire wickbetween the evaporator unit headersand the suction line of themechanical refrigerating system will efliciently return the oil to thecompressor without in any way affecting the working conditions of theevaporator.

While the invention will be hereinafter described and illustrated inconnection with embossed sheet metal evaporator units, it should beunderstood that the wire wick means for returning oil to the compressoris adapted for use in other types of evaporator units including the typebuilt up from tubes and headers.

A feature of the invention includes the emfrom the unit withoutdischarging liquid refrigerant therewith.

A specific object of the invention is to provide a device for removingoil from liquid refrigerant by capillary action without loss ofrefrigerant.

Another object of the invention is to interpose a device between aheader and a suction line of an evaporator unit for eifecting transferof oil from the header to the supply line by capillary action withouteifecting removal of liquid refrigerant therewith.

- Other and further objects of th invention will become apparent tothoseskilled n the art from the following detailed description of the annexedsheets of drawings which disclose preferred embodiments of theinvention.

0n the drawings: Figure 1 is a-diagrammatic elevational'view of amechanical refrigerating system of the compressor-condenser-evaporatortype. including an evaporator unit according to the invention. I Figure2 is an, enlarged top plan view of the evaporator unit shown in Figure 1taken along the line II- -II of Figure 1. 'Figure 3 is a sideelevational view of the evaporator unit shown in Figure 2 taken alongtheline IlI-III of Figure 2. I

Figure 4 is an enlarged vertical cross-sectional view, with parts-inelevation, taken along the line IVIV of Figure 2.

Figure 5 is a fragmentary end elevational view" taken along the line V-Vof Figure 3.

Figure 6 is a small plan view of a woven mesh material illustrating themanner in which the same is rolled into the wick shown in Figure 4.

Figure 7 is anend elevational view of a modifled form of evaporator unitequipped with a wire wick oil returning means according to thisinvention.

\ Figure 8 is a fragmentaryplan view, with parts in horizontal section,taken along the line VIII- VIII of Figure 7.

bossing of sheet metal evaporator units to receive the wire wick oilreturning means.

It is, then, an object of the invention to provide heat exchangers,.such as evaporator units,-

As shown on the drawings:

In Figure 1 the reference numeral I0 designates a base or support for anelectric motor II and a refrigerant compressor l2. The motor drives thecompressor l2 through a belt l3.

Compressed refrigerant from the compressor l2 flows through a tube orconduit H into a condenser l5 where it is cooled and condensed intoliquid .form. The condensed refrigerant then flows through a tube orconduit it into a receiver tank" from which it is directed, as needed,into a valve I! which injects liquid refrigerant, as needed, through atube!!! into the shelf tube 2| of an evaporator unit 22. The refrigerantflowing through the shelf tube 2| cools the shelf and is directedthrough a tube 23 into an embossed header 24011 the bottom of theevaporator unit 22. The header 24 communicates with a plurality ofembossed expansion ducts 25 ex tending around the sides and bottom ofthe evaporator unit and the refrigerant circulates through the ducts 25into the headers such as 26-on each side of the unit. A suction conduit21 is embossed on the sides and bottom of the evaporator unit andcommunicates with the suction line :28 back to the inlet side ofthecompressor l2. Ac-

cording to this invention wire wick means such as 29 are interposedbetween the headers such as 26 and the tops of the suction conduit 21for removing oil from the liquid refrigerant 'in the headers withoutremoving. liquid refrigerant therewith; The suction line '23 thusreceives gasifled refrigerant and oh from the evaporator unit.

The oil is thus returned to the compressor for performing itslubricating function while the gasifled refrigerant is compressed by thecompressor form horizontal flanges' 30 adapted for attach- 23communicating with the header .24.

sired, the tube 2| can include and be a part of stop for articlesmounted on the bottom wall of the unit. Upturned flanges 33c are alsoprovided at the rear end of the shelf 33 to act as stops for ice traysor other articles mounted on top of the shelf.

In order to cool the shelf 33 the inlet tube from the valve l9 describedin Figure 1 communicates with a tube 2| secured to the underof the tubeas shown in Figure 2 is suflicient.

The tube 2| discharges into a connecting tube If dethe tube 23 as shown.Liquid refrigerant thus flows from-the valve l9 through the tube underthe shelf and thence into the header conduit 24 inent to the roof of arefrigerator cabinet so as to suspend the unit in the top of thecabinet.

Th outer sheet of the unit 22 is embossed to form the header duct 24extending longitudinal- Both at the bottom of the unit, from which it isdistributed through the expansion ducts 25 into the headers 26. Any oilentrapped with the refrigerant will float on top of the same in theheaders 26. As the liquid refrigerant boils off in the header, the gasor vapors therefrom are .dis-

duct 21 and back to the compressor.

The liquid refrigerant is preferably kept at a level in the evaporatorheaders 26 beneath-the tops thereof. i

According to this invention woven wire mesh material such as a copperscreen 35 (Figure 6) is rolled into a tight roll 36 toi'orm a capillaryactiv wick. Copper wire of about 80-mesh is highly efllcient but itshould be understood that other metal wicks can be used in place ofwoven wire. Fabric wicks are also operable but, since the evaporatorunit is formed by a brazing oper-,

to form elongated cylindrical headers 26 extending longitudinally alongthe tops of the side walls of the unit and communicating with the topsof the expansion ducts 25. The expansion ducts 25 terminate in thebottoms of the headers 26.

c The suction duct or discharge duct 21 of the evaporator unit isembossed in the outer sheet of the unit and extends from the tops of theside walls around the sides and bottom of the unit' to an embosseddome-like portion 3| on the inside sheet of the unit. The suction duct21 does not communicate with the header 24. as illustrated in Figure 5but discharges into the dome portion 3| which receives'th suction line28 communicating with the inlet side of the compressor l2 as explainedabove.

In this form of evaporator unit,- therefore, the suction or return ductis embossed in th unit and extends around the sides and bottom of theunit so that it can be exhausted through a single tube leading to thecompressor unit. The ern-J bossed suction duct 21 receives gasifledrefrigerant from the tops of both headers 26 through embossed ducts 32on the inner sheet of the unit.

' Each of these ducts joins the top of a header26 flanges 33a which areriveted as at 34 to the side walls of the unit. The shelf also has adependent flange 33b at the rear end thereof to act as a 75 bossedcylindrical headers 43 in the. top of the material should be capable ofresisting the brazing temperature.

if desired.

The tightly rolled wire mesh wicks 29 are insertedthrough-U-shaped tubes31 and project tom portion of the headers 26 and also extends into thetop portion of the suction tubel'l. Oil floating on top of the liquidrefrigerant in the header passes up the wick 29 by capillary action,through the tube 31 and into the suction tube 21 where it is removedalong with the gasifled refrigerant. The refrigerant does not flow upthe wick by capillary action and, as a result,

only the oil is pwsed through the tubes 31.

If desired apassageway can be embossed on either or both of the metalsheets forming the evaporator unit in place of the tubes 31. The wick 29can be laid between the sheets in the embossed passageway providedtherefor when tion.

In th modification disclosed in Figures 7 and 8, a U-shaped evaporatorunit ill composed'of brazed-together metal sheets bent in the shape of aU has the outer sheetthereof embossed witha plurality of ducts such asexpansion ducts 4| extending around the sides and bottom of the unit andcommunicating with an embossed header 42 in the bottom of the unit andwith the em- Asbestos wicks might be used assembled for the brazingoperaunit. The side walls of the'unit are provided with outturnedflanges 40a. for suspending the unit from the ceiling of a refrigeratorcabinet. In place of the embossed suction duct '21 the headers areconnected through a .suction tube V bridging the top portion of theunit. The suction tube. 44 communicates with the :top portion of eachheader near one end thereof. The mlddl of the tube 44 is connected withthe tube or duct 28 leading to the compressor of the refrigeratingsystem.

According to the invention 9. rolled wire mesh screen forming a wick 45is inserted .in the tube 44 with the ends 450 thereof extending into theheaders 43 and terminating near the bottom bottom of the unit connectingthe tops of the headers, and wick devices bridging the headers and thetops of the passageway for removing oil from the headers into thepassageway.

2. A sheet metal evaporator unit comprising a pair of secured-togethercontiguous metal sheets defining the side walls and "bottom-of a sharpfreezing chamber, said sheets being embossed to define a header on eachside wall, atv least one thereof. An intermediate portion 45b of thewick is inserted into the suction tube 28.

- In the unit 40 refrigerant is fed into the inlet duct or header 42,passes upwardly through the expansion ducts 4| into the headers 43 fromwhich it boils oil or gasifles and the vapors pass through the suctionduct 44 into the suction tube 28. However, oil entrained withtherefrigerant will float on top of the liquid refrigerant in theheaders 43 and will travel upward, by capillary action, through the wick45 into the suction line a 28 where it can be removed together gasifledrefrigerant.

The evaporator unit 40 can be equipped with a sheet metal shelf 46having downturned side flanges 46a riveted to the side walls of the unitby means of rivets such as 41. 'The rear end of the shelf can have adownturned central flange portion 46b acting as a stop for articlesmounted on the bottom wall of the unit under :the shelf. The rear ofthe. shelf can also have an upturned flange 460 on each side of thedownturned flange to act as stops for ice trays mounted on the shelf.

From the above descriptions it should be understood that the inventionnow provides simple,

with the inexpensive wick means for removing oil or other lubricant fromheat exchangers such as evapo- 'rator units. The invention specificallyprovides sheet metal evaporator units equipped 'with wick means betweenthe headers and the suction lines for removing oil from the headerswithout removing refrigerant before the refrigerant has been completelyspent.

a In one form of the invention the sheet metal evaporator unit isprovided with an embossed v suction duct andembossed headers togetherwith a capillary path between the headers and the suction duct. Inanother form of the invention a stamped sheet metal evaporator unit hasthe headers thereof joined by a bridging suction pipe for gasifledrefrigerant and this pipe contains a wick extending into the bottoms ofthe headers for effecting a flow of oil into the suction line.

It will, oi course, be understood that various 'details of constructionmaybe varied through a wide range without departing from the principlesof this invention and it is, therefore, not the purpose to limit thepatent granted hereon otherwise than necessitated by the scope of theappended claims.

We claim as our invention: I 1. A sheet metal evaporator unit comprisingsecured-together contiguous metal sheets deflning the side walls andbottom of a sharp freezing chamber, at least one of said sheets beingembossed to deflne a header on each side wall, at

least one of said sheets being further embossed to define a passagewayalong the side walls and 7 'of said sheets being further embossed todeflne a passageway Joining the tops of each header, a

single exhaust communicating with said passageway, means definingadditional passageways joining the tops of each header with the tops ofsaid first mentionedpassageway, and metal wick members extending throughsaid additional passageways and projecting into said headers and saidfirst mentioned passageway for removing oil from the headers bycapillary action.

3. In an evaporator unit composed .of inner and outer contiguoussecured-together metal sheets defining refrigerant circulation ducts andheaders communicating withthe ducts together with an embossed flute onone sheet connecting the tops of the headers, the improvement whichcomprises wick. means interposed between the headers and said flute forconveying oil from the headers into the flute.

4. A U-shaped evaporator unit having header chambers in each side wallthereof and a suction tube bridging the side walls and communicatingtube and pipe having the ends thereof extending into the bottom portionsof said headers and having an intermediate part thereof inserted intosaid tube.

6. A sheet metal evaporator unit comprising secured-together inner andouter contiguous metal sheets enclosing a sharp freezing chamber andbeing embossed to provide refrigerant circulating passageways around thechamber, said sheets being further embossed to provide headers at thetop ends of said passageways and communicating with the passageways,said outer -sheet being further embossed to provide a discharge flutearound the sides and bottom of the unit, saidinner sheet being embossedto provide a passageway joining the tops of the headers with the tops ofsaid flute, U-shaped metal tubes connecting the tops of the headers withthe tops of the flute, and wick means in said U-shaped tubes projectinginto the headers and flute for conveying oil out of the headers.

- '7. In an evaporator unit including means deflning a header chamberand means deflnlng a I suction line in laterally spaced relation fromsaid header chamber for discharging refrigerant out of the headerchamber, the improvement which comprises a U-shaped tube bridging thespace between the header chamber and the suction line and having thelegs thereof in communication with the header and the suction line, anda tightly rolled wire mesh rod in said tube having the ends thereofprojecting. from said legs of the tube into the liquid-receiving portionof the header chamber and into the suction line respectively.

8. A sheet metal evaporator unit composed of U-shaped inner and outermetal sheets secured together in contiguous relation and embossed to .5

provide a header chamber in the top portion of each leg 01' the Utogether with refrigerant circulating ducts extending from the headerchambers around the sides and bottom of the U,.the

BERNARD C. JOHNSON. EDGARD C. FRANCO-FERREIRA.

